350 just not quite right

[spectrumad]

I have a Pontiac 350 in a 1971 Lemans. Bored .030, mild cam, headers, Quick Fuel carb, small valve heads. Everything is rebuilt or new. With timing set at 14 degrees BTDC, it runs with a loping idle, as if it had a big cam. If I roll the timing back to about 34 BTDC, the idle smooths out and gains about 250 RPM. When driving the car there is not a big difference in power either way. Anyone? The tone of the exhaust just does not sound quite right either way, the tone is just off.

Anyone?

 

[melsg5]

there is no way you can be setting your initial timing to 34 degrees without the engine pinging to the point of damage. Either your timing marks are off due to the harmonic damper rubber having permitted the outer ring to slip or you are not connecting the timing light to #1 cylinder or there is something wrong with the mechanical advance mechanism in the distributor. So to start with the second possibility are you connecting the timing light to the plug wire on the drivers side furthest to the front of the engine? Have you removed the cap and rotor and observed that the weights move freely to fully advance and fully retract? For the first one can you fabricate a top dead center tool to determine if the outer ring has slipped or can you see any separation between the hub and outer ring ?

 

[spectrumad]

Yes, I am on the #1 cylinder. The distributor is new, but that means nothing anymore. I will pull the cap and check the weights. The balancer is new as well, but I will check to make sure my marks are not off. I didn't notice any seperation. I will post when I can check it out. Thanks

 

[melsg5]

A new distributor, what manufacturer and what part number?
Is it the correct balancer, what manufacturer and part number? I assume it is new not used.
Do you have any other modifications to the ignition you have not mentioned, not using an MSD box?
What timing light are you using?

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[cammerjeff]

Are you blocking off the Vacuum advance unit (if your dist is so equipped)? I agree that there is no way your car is running with 34 degrees of initial advance, if you have more than 12 to 14 your engine will be very hard to start, and may even kick back (rotate the wrong way) when it tries to start.